If a judge approves it, the deal would set a 2018 deadline for the administration to decide whether Endangered Species Act protections are needed for species as diverse as the wolverine, Pacific walrus and Miami blue butterfly.

A similar agreement in May with the group WildEarth Guardians excluded the wolverine and walrus.

Some of the plants and animals in the agreement were first proposed for protection soon after the passage of the Endangered Species Act in 1973. Instead, they languished for decades on a list of candidate species the government could not afford to help.

The deal covers 258 of the candidate species and another 499 plants and animals for which the Center for Biological Diversity has filed court petitions seeking greater protections, said the group's executive director, Kieran Suckling.

"We're dealing with the ultimate stakes of life and death with this settlement," Suckling said. "If these 757 had to wait much longer, many of those would go extinct as well."

The species that were included in the petitioning process will be reviewed for a determination on whether they warrant protection. That's the first step in listing a plant or animal as threatened by or in immediate danger of extinction.

Government officials have said the backlog has been made worse by lawsuits that have distracted the Fish and Wildlife Service from needed scientific reviews and restoration work.

"This work plan will allow the service to more effectively focus our efforts on providing the benefits of the ESA to those imperiled species most in need of protection," Fish and Wildlife Service Director Dan Ashe said.

The settlement was filed for approval with U.S. District Judge Emmet Sullivan.